Efficient generation of dopaminergic neurons from mouse embryonic stem cells enclosed in hollow fibers.

Transplantation of dopamine neurons is a promising approach to treat Parkinson's disease. Embryonic stem (ES) cells are expected to be a cell source of the dopaminergic neurons. Various difficulties, however, need to be overcome to realize cell therapy of Parkinson's disease using dopaminergic neurons from ES cells. For example, they are highly sensitive to enzymatic treatment and physical dissociation, and the patient's immune system may attack the transplanted cells. In this study, we attempted to induce dopaminergic neurons from mouse ES cells enclosed in hollow fibers using conditioning medium from PA6 cells, the stromal cells derived from skull bone marrow. beta-tubulin type III positive cells and tyrosine hydroxylase positive cells were efficiently derived in hollow fibers after 16 days in culture, and dopamine release was observed when the hollow fibers containing cells were exposed to 56mm KCl for 15min to induce dopamine release through depolarization of the neurons. By our procedure, enclosure of dopaminergic neurons in hollow fibers was easily performed without loss of cells, and the hollow fiber membrane is expected to efficiently protect dopaminergic neurons from mechanical disturbances and attacks by the host immune system. Although there are many issues, especially related to immuno-isolation, that still remain to be addressed, we believe that differentiation of ES cells within hollow fibers is one of the crucial procedures so that cell therapy of Parkinson's disease can be realized.